Organization

The 14th Defense Battalion was commissioned on January 15, 1943 in the field on Tulagi in the Solomon Islands. Personnel for the battalion were sourced from two batteries from the 5th Defense Battalion and a 5"/51 caliber gun 5-inch battery from the 9th Defense Battalion that were remaining behind on Guadalcanal and Tulagi. Because a majority of the battalion's original personnel were from the 5th Defense Battalion the 14th took on the nickname "Five:Fourteenth."^[5]

Nouméa & the Bismarck Archipelago

The battalion remained in the Solomons until September 1943 when its headquarters was relieved by United States Army units and departed for Noumea, New Caledonia on September 16, 1943. Arriving four days later it disembarked and established its command post near TonTouta. The rest of the battalion was relieved within the next month and the entire battalion was present on Nouméa by October 22 responsible for air and coastal defense of the area.

On March 7, 1944, most of the battalion loaded gear onto seven different ships and departed Nouméa. The convoy arrived on Guadalcanal on March 12. Prior to departing the island, a composite antiaircraft battery from the 14th was assembled as part of a small Marine task force to support the United States Army during its assault on the St Matthias Islands. The battery landed on the southeast corner of Emirau in support of the 4th Marine Regiment.^[6] There was no opposition on the island and the Seabees set out building an airfield immediately.^[7] Another detachment from the battalion supported the 1st Marine Aircraft Wing's occupation of Green Island. Seizure of both of these islands within the Bismarck Archipelago were critical in the effort to bypass the main Japanese airfield at Rabaul.^[7]

Guam

In May 1944 the Marine Corps organized a unit of 51 Marines called the 1st Provisional Smoke Screen Unit. Its mission was to utilize smoke generators during enemy bombing raids with the purpose of obscuring friendly targets. This unit was attached to the 14th to be tested during its next operation.^[2] During the first week of June 1944 the battalion was divided into three echelons to be part of the Southern Attack Force for the upcoming assault to recapture Guam. The first two echelons departed Guadalcanal in a different convoy however they eventually linked up at Eniwetok on June 28. The third echelon remained until mid-July when they also embarked upon naval shipping. The first two echelons departed Eniwetok on July 17.

On the morning of July 21, 1944 an advanced party from the 14th Defense Battalion went ashore on Guam from the USS President Monroe (AP-104). The rest of the battalion came ashore a few hours after the initial assault waves stormed the beach. By night of the first day all of the battalion's anti-aircraft batteries were emplaced ashore with some also providing direct fire support for Marines of the 3rd Marine Regiment.^[8] On July 23, the battalion received orders to occupy Cabras Island in Apra Harbor. From Cabras Island the battalion was able to continue its mission of providing air defense for Orote Field and provide flanking artillery fire for Marines on the Orote Peninsula and in the Northern part of the island.^[9] The battalion's command post moved from Cabras to the Orote Peninsula on August 5. The smokescreen unit that had been attached to the battalion prior to the battle was disbanded in July 1944 because the concept did not prove feasible.^[2] During the battle the battalion served under the command of the 12th Marine Regiment.^[10]

As the war progressed, the Marine Corps removed coastal artillery from the defense battalions in order to form additional heavy artillery units for the Fleet Marine Force.^[3] Because of the divestiture of the coastal defense mission, the battalion was re-designated as the 14th Antiaircraft Artillery Battalion on September 1, 1944.^[3] The battalion spent the remainder of their time as part of the garrison force on Guam and was decommissioned there on June 30, 1945 before the end of the war.^[2]